Nebular Hypothesis (redirected from Planetary formation)

nebular hypothesis: see solar system.

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nebular hypothesis [′neb·yə·lər hī′päth·ə·səs]

(astrophysics)

A theory, proposed in 1796 by Laplace, supposing that the planets originated from the solar nebula surrounding the proto-sun; as the sun cooled, it contracted, rotated faster, and thus caused a ringlike bulging at the equator; this bulge eventually broke off and formed the planets; Laplace further theorized that the sun and other stars formed from clouds of nebulous matter; the theory in this form is not accepted.

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Nebular Hypothesis 

a cosmogonical hypothesis which assumes that the solar system (and celestial bodies in general) was formed out of a rarefied nebula. The term “nebular hypothesis” originated in the 19th century in connection with the Laplace nebular hypothesis. Later, the term was also used in Kant’s hypothesis and in other theories that assumed the formation of celestial bodies from nebulae of gas or dust. The term “nebular hypothesis” is not usually used in relation to modern cosmogonical hypotheses. (SeeCOSMOGONY.)